It's simple physics: If you square up an Aroldis Chapman fastball, it goes a long way.

Chase Headley squared up a 99 mph heater with two outs in the ninth inning Tuesday night. It went out to left field to lift the San Diego Padres to a 2-1 victory over the Reds before a crowd of 23,269 at Great American Ball Park.

Chapman, in his second game back since that horrific line drive to the face, struck out the first two hitters he faced. He threw a 100 mph strike to Headley. Chapman missed with a 101 mph pitch.

"That's what happens," Reds manager Bryan Price said. "Guys are going up and trying to get the bat started. If they can get the barrel to it, the velocity is going to do the job."

Cincinnati Reds relief pitcher Aroldis Chapman (54) gave up a solo home run to San Diego Padres third baseman Chase Headley (7) in the ninth inning, losing the game 2-1 at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds relief pitcher Aroldis Chapman (54) gave up a solo home run to San Diego Padres third baseman Chase Headley (7) in the ninth inning, losing the game 2-1 at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

San Diego Padres third baseman Chase Headley (7) hit the go ahead solo home run in the ninth inning off Cincinnati Reds relief pitcher Aroldis Chapman (54) at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

San Diego Padres celebrate after a third baseman Chase Headley (7) solo home run in the ninth inning off of Cincinnati Reds relief pitcher Aroldis Chapman (54) at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds shortstop Zack Cozart (2) gets the out on San Diego Padres second baseman Jedd Gyorko (9) ending the top of the ninth inning at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds relief pitcher Aroldis Chapman (54) gave up a solo home run in the ninth inning to San Diego Padres third baseman Chase Headley (7), losing the game 2-1 at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds first baseman Joey Votto (19) makes the out at first base on San Diego Padres shortstop Everth Cabrera (2) in the first inning at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds Joey Votto (19) walks through the dugout after being tagged out at second base by San Diego Padres shortstop Everth Cabrera (2) at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds third base coach Steve Smith (35) and Brandon Phillips (4) talk at third base in the first inning against the San Diego Padres at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds second baseman Brandon Phillips (4) back hands the ball to make the play at first base in the fifth inning against the San Diego Padres at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

Cincinnati Reds first baseman Joey Votto (19) gets out of the way as he makes the out at first on San Diego Padres center fielder Will Venable (25) in the fifth inning at Great American Ball Park. (Photo: The Enquirer/Jeff Swinger)

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But Chapman should have been protecting a lead, not entering a tie game. The Reds left eight runners on and were 1-for-9 with runners in scoring position. The loss dropped the Reds to 6-12 in one-run games.

"One-run games again," Price said. "There's always certain things that happen that could change the outcome of a ballgame. Sometimes it's putting a ball in play, sometimes it's throwing a strike or executing a bunt play or fielding a ground ball. Tonight, we had 10 base-runners. We didn't get enough in and lost the game 2-1."

Mike Leake pitched well enough to win. He allowed one run on two hits – both to Seth Smith – over eight innings. He walked one and struck out five.

"Leaker couldn't have been any better," Price said. "Early on, he was pulling his cutter and fastball just a bit. He made a great adjustment. He and Brayan (Pena) worked really well together. He had that nice mix of sinker-cutter going and just made pitch after pitch."

Leake is joining Johnny Cueto in the tough-luck ranks. The Reds have scored a total of five runs over Leake's last four starts. The Reds have lost all four of those games.

"It's part of the game," Leake said. "I'd rather have good defense behind me than runs. You've got to score runs to win. Me personally, I love defense and tonight was a good display of it."

As much as a one-run loss hurts for the Reds, manager Bryan Price sees a silver lining in Mike Leake's game. He allowed one run on two hits.

Price remains positive and upbeat, despite the fact that the Reds have the most one-run losses in baseball.

"The tide'll turn," he said. "It's not the start we envisioned. We're not hitting on all cylinders yet. However, the starting pitching is showing up and getting better and giving us a chance to win most every night. That's going to pay dividends."

San Diego right-hander Andrew Cashner limited the Reds to one run on seven hits over seven innings.

Billy Hamilton led off the first with a ball down the line that made it into the left-field corner. Hamilton made it to third with ease for his second triple in as many games. An out later, Brandon Phillips lined a 97 mph fastball over the second baseman's head for an RBI single.

It looked like the Reds had a chance for a big inning when Joey Votto hit one off the wall in right. But right fielder Seth Smith played the carom perfectly and his strong throw nailed Votto at second. Todd Frazier grounded out to end the inning.

So the big threat netted one run.

"We're preaching to be aggressive," Price said. "We're trying to create more scoring opportunities. Joey busting his tail to get into scoring position is something we encourage. Seth Smith made a great throw."

Leake pitched out of two-out trouble in the first. He worked 1-2-3 innings in the second and third.

But Smith led off the fourth with a double. He went to third on Carlos Quentin's groundout. Leake hit Headley with a pitch. Jedd Gyorko put a charge into one to right. Chris Heisey ran it down at the wall. The sacrifice fly tied it at 1-1.

"They manufactured a run off me," Leake said. "There's nothing I could have really done. They did a nice job getting that guy in."

The Reds missed a chance to untie it in the bottom of the fourth. Frazier led off with a double to extend his career-high hitting streak to 12, but the Reds could not move him off second.

The Reds missed another chance to untie it in the sixth. Phillips led off with a double – his third hit of the game. Votto followed with a walk. Frazier sent one to the warning track in right. Phillips moved to third on the play.

Ryan Ludwick reached on catcher's interference to load the bases. But Heisey grounded one back to Cashner, who threw home to force out Phillips. Zack Cozart popped meekly to first to end the threat.

That was the last threat. The Reds only had one baserunner over the last three innings.